Fluid heaters of the general type herein described are known and generally comprise an elongated heating element comprised of a continuous length of resistance wire enclosed in a cylindrical insulating tube, generally of quartz. The insulating tube is mounted within a close-fitting metal sheath to protect it from breakage. This metal sheath with its enclosed heating element is in turn mounted within an airflow cylinder which is fixedly mounted within a cylindrical heater housing. One end of the heater is adapted for heated fluid exit and a second end is adapted to provide fluid entrance as well as means for making electrical connection to the heater element. Heaters of this type have generally worked well; however, fluid leakage at the exit reduced the desired efficiency by allowing some of the fluid to escape before it was sufficiently heated.